Work around for the checksum in languages that do not support integers with more than 30 chars:
Piece-wise calculation D mod 97:
The problem here lies in the fact that mendix uses longs but does not allow you to parse it. What you can do is create a java action that parses the string to a long value and then finish your calculation.
Do the checksum on a string level, parseInteger(substring , pos, 1)
Edit: There seems to be some java implementations available on internet like this
Rene - I think the number is too large for an int variable - max length for int is 2 to the 63rd power minus 1. I suspect float has a similar limitation. Mike
I had same problem and used java class designed for handling big numbers: BigInteger here you can execute mod 97